Bobbin case



Sept. 18, 1956 F. s. HOWARD BOBBIN CASE Filed Dec. 30, 1953 ai@ Se@ Patent BOBBIN CASE Frank S. Howard, Round Lake, lll., assignor to Blrtmau Electric Company, a corporation of Illinois Application December 30, 1953, Serial No. 401,123 2 Claims. (Cl. 112-251) This invention relates to a bobbin case for a sewing machine for removably retaining the bobbin during the sewing operation.

In rotary hook sewing machines the rotary hook structure, which includes a loop-forming beak, is located immediately beneath the needle in the bed of the machine and has retained therein a bobbin containing thread which forms the bottom portion of the stitched seam. Because of its location, it is ordinarily dicult to remove the bobbin from the bobbin case when it becomes necessary to rewind the bobbin or substitute a filled bobbin for an empty one. This is true because of the limited space surrounding the bobbin case and because ordinarily only one or two fingers can be used in manipulating the case and in removing the bobbin therefrom.

Another disadvantage of prior bobbin case constructions is that the bobbin is sometimes dropped while it is being inserted or removed so that not only is it ditlicult to retrieve, but where the bobbin is wound with thread the outer portions of this thread often become unwound. Another disadvantage is that prior bobbin cases have elaborate latching arrangements for holding the bobbin case together with the bobbin rotatably mounted therein. These and other disadvantages of prior bobbin cases have been overcome in the present invention.

The invention will be described as related to the embodiment shown in the accompanying drawings.` Of the drawings:

Figure 1 is an end elevational view of a rotary hook assembly including bobbin case constructed according to this invention;

A Figure 2 is an elevation similar to Figure l, but showing the opposite side of the structure;

Figure 3 is a sectional elevational view taken substantially along line 3-3 of Figure 1;

Figure 4 is an edge elevational view of the structure;

Figure 5 is a side elevational View of the removable cap of the case showing the inside thereof;

Figure 6 is an edge elevational view of the cap of Figure 5.

The bobbin case disclosed herein is of the type adapted to be used in a conventional rotary hook sewing machine of the type disclosed in the copending application Serial No. 309,015, led September 1l, 1952, of the same inventor. The bobbin case includes a rotary loop taker 10 having a cylindrical rearwardly-extending portion 11 thereon adapted to be mounted on the rotary shaft of the machine for rotation of this loop taker. The loop taker is provided with a thread-engaging beak 12 to engage the thread from the needle and cast a loop about the bobbin thread in the customary manner.

The bobbin thread is normally wound on a bobbin 13 conned within the bobbin case 14. This bobbin case comprises a cup-shaped body section 15 held Within the loop taker 10 by means of a circumferential rib 15a held within a similarly shaped groove 10a in the loop taker. This body section 15 is provided with an upwardly-cxtending part 15b, adapted to be held within a portion of the machine bed beneath the needle drive bar in order to prevent rotation of the bobbin case when the loop taker is rotated. Similar constructions are conventional and one such is illustrated in the above mentioned application Serial No. 309,015.

Cooperating with the body section 15 in retaining a bobbin 13 in the bobbin case 14 there is provided a cap section 16 having a cylindrical side 16a telescopically received within the body section 15 in the manner illustrated most clearly in Figure 3. This cap section 16 is provided on its outer surface with an essentially V shaped spring 17 having a nose 17a extending upwardly and lying within a groove in the extended part 16d 'of the cap section 16 and side pieces 17b and 17C held in slots 16b and 16C, respectively, in the cap section 16. The spring 17 is held in place by means of a screw 18, engaging the extended outer end 19a of an inwardlyextending axial post 19 within the cap section 16. The thread from the bobbin is adapted to be lead through an opening 17d and between the spring nose piece 17a and the part 16d of the cap section 16. The spring applies tension to the thread being pulled between these parts. This construction is conventional in rotary hook sewing machines.

The inwardly-extending axial post 19 within the cap section 16 is hollow to provide a cylindrical shell 19b open at the inner end as indicated in Figure 3. Positioned within this shell 19b is a permanent magnet 20 having its inner end recessed inwardly of the inner end of the cylindrical shell 19b. When the parts are assembled in the manner shown in Figures l to 4 inclusive of the drawings, the inner end of this shell is occupied by a short cylindrical stud 21 that is axially aligned and fastened to the inner Wall to project outwardly from this inner wall 15a` of the body section 15.

The cylindrical shell 19 is preferably made of a nonmagnctic metal such as brass and the stud 21 is made of a magnetic metal such as steel. When these parts are in their assembled relationship the magnet serves to hold the cap section 16 and bobbin 13 within the body section as is shown in the drawing.

The construction described and claimed herein, in-

cluding the magnet illustrated at 20, has a number of very important advantages. Thus, the construction not only serves to retain the bobbin in place and to retain the body and cap sections assembled, but it also serves to hold the metal bobbin within the cap section 16 `when this cap section is removed from within the body section 15. There is thus little danger that the bobbin will be accidentally dropped when the parts are assembled and disassembled. Furthermore, the magnet serves as a drag on the bobbin to cause a slight friction while the thread is being unwound from the bobbin during the sewing operation. This serves t0 keep the bobbin thread taut, gives better control over the thread and aids in preventing entangling of the thread with the rotating parts of the adjacent structure. Furthermore, as this friction drag operates on the center part of the bobbin as this is the part that engages the magnet structure, this drag is always constant regardless of the amount of thread on the bobbin. The preferred construction wherein the non-magnetic cylinder illustrated at 19b surrounds the magnet, serves to concentrate the magnetic lines of force at the inner end of the cylinder. This makes the attachment of the cap section to the body section more secure. The magnet construction also precludes the necessity of a separate latch to hold the cap section in the body section. This elimination of a latch serves to save space and decrease cost. Furthermore, with the structure of this invention it is a simple job to remove the cap section and bobbin and to assemble the cap section and bobbin in the body section.

The pr'ovision of the short stud illustrated at 21 has a niimbe'r 'of 'iiportant advantages. Thus, 'it serves to 'aid in positioning the cap section within the body section, anchors the inner end of the cylinder and aids in Apreventin'g 'twisting of thefcap vsection'within the body section.

Having described my invention as related to the embo'diment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be 'construed 'broadly within its 'spirit and scope as set ont in the accompanying claims.

I elaim:

1. A sewing machine bobbin case, comprising: a cupshaped body section; a 'removable Vcap section associated therewith to dene abobbin receiving space; a hollow axialmem'b'e'r of non-magnetic material on the cap ser tion'ha'ving an open inner en'd extending toward the body section when the sections are assembled; a magnet withinthe `hollow axial member recessed within said open inner Vend so that said end Vextends 'therebeyondg and an axial magnetic metal stud on said body section normally projecting into said open Vinner end `and positioned adjacent to said magnet when said sections 'are assembled.

2. A sewing machine bobbin case, comprising: a cup- `Shp1ibby hSE'C'D; 'a mvbl'e Cap `S'6 C`ti'0i1 a'S'SUCiel therewith to define a bobbin receiving space; a hollow axial member of non-magnetic material on one of said sections having an open end extending toward the other section when the sections are assembled; a. magnet within the hollow axial member recessed within said open end so that said end extends Ytherebeyond; and an axial magnetic metal stud fon said 'other section normally projecting into said open end and positioned adjacent to said magnet when 'said 'sections a'r'e assembled.

- References Cited in the file `of this patent UNITED STAT-ES PATENTS 1,316,444 Hayes Sept. 16, 1919 2,034,506 Colegrove et al Mar. 17, 1936 2,521,885 Vasquez Sept. 12, 1950 2,527,391 Blais Oct. v24, 1950 2,543,475 Slodysko f Feb. 27, 195]. 2,586,900 Alderman Feb. 26, 11952 2,673,541 Bieserneyer A Mar. 30, 1954 

